Further studies on trade winds during the glacial cycles

Core V19-301 (south of Cape Verde Islands) has been analysed in detail for (i) size distribution of quartz grains, (ii) mineralogy, (iii) colour and organic carbon (iv) G. menardii foraminifera, and (v) total foraminifera and carbonate. These results are compared with those previously obtained on core V23-100 (north of Cape Verde Islands). It is believed that the carbonate variations can be used to establish simultaneity between the cores, and thus the following climatic data emerge: ( a ) During glacial stages the trade winds were more vigorous than normal for the region north of the Cape Verdes; but the wintertime Harmattan was weaker than normal for the region south of the Cape Verdes. ( b ) The land to the north of Dakar remained desert, and was especially arid during glacials, whereas to the south of Dakar conditions oscillated between desert during interglacials, and savannah during glacials, ( c ) These wind and rainfall oscillations were more rapid and less excursive at around 0.7 Ma than they were in later glacial cycles.

Download Full-text

Assessing the Sensitivity of Main Crop Yields to Climate Change Impacts in China

Atmosphere ◽

10.3390/atmos12020172 ◽

2021 ◽

Vol 12 (2) ◽

pp. 172

Author(s):

Yuan Xu ◽

Jieming Chou ◽

Fan Yang ◽

Mingyang Sun ◽

Weixing Zhao ◽

...

Keyword(s):

Climate Change ◽

Crop Yield ◽

Food Production ◽

Crop Yields ◽

Climatic Factors ◽

Climatic Data ◽

The South ◽

The North ◽

Output Elasticity ◽

The Impact

Quantitatively assessing the spatial divergence of the sensitivity of crop yield to climate change is of great significance for reducing the climate change risk to food production. We use socio-economic and climatic data from 1981 to 2015 to examine how climate variability led to variation in yield, as simulated by an economy–climate model (C-D-C). The sensitivity of crop yield to the impact of climate change refers to the change in yield caused by changing climatic factors under the condition of constant non-climatic factors. An ‘output elasticity of comprehensive climate factor (CCF)’ approach determines the sensitivity, using the yields per hectare for grain, rice, wheat and maize in China’s main grain-producing areas as a case study. The results show that the CCF has a negative trend at a rate of −0.84/(10a) in the North region, while a positive trend of 0.79/(10a) is observed for the South region. Climate change promotes the ensemble increase in yields, and the contribution of agricultural labor force and total mechanical power to yields are greater, indicating that the yield in major grain-producing areas mainly depends on labor resources and the level of mechanization. However, the sensitivities to climate change of different crop yields to climate change present obvious regional differences: the sensitivity to climate change of the yield per hectare for maize in the North region was stronger than that in the South region. Therefore, the increase in the yield per hectare for maize in the North region due to the positive impacts of climate change was greater than that in the South region. In contrast, the sensitivity to climate change of the yield per hectare for rice in the South region was stronger than that in the North region. Furthermore, the sensitivity to climate change of maize per hectare yield was stronger than that of rice and wheat in the North region, and that of rice was the highest of the three crop yields in the South region. Finally, the economy–climate sensitivity zones of different crops were determined by the output elasticity of the CCF to help adapt to climate change and prevent food production risks.

Download Full-text

Circulation Marine de la Baie de Cintra (Sud du Maroc) par Modèle Hydrodynamique 2D

European Scientific Journal ESJ ◽

10.19044/esj.2017.v13n12p175 ◽

2017 ◽

Vol 13 (12) ◽

pp. 175

Author(s):

Hilmi Karim ◽

Makaoui Ahmed ◽

Ettahiri Omar ◽

Idrissi Mohammed ◽

Abdellaoui Benyounes ◽

...

Keyword(s):

Hydrodynamic Model ◽

Coastal Circulation ◽

The South ◽

Trade Winds ◽

The North

The marine circulation of Cintra bay located at Dakhla Oued Eddahab area (south of Morocco 23°08’N-16°20’W) has been studied from October to November 2016 by 2D hydrodynamic model. This study aims to understand the marine circulation of this bay and its hydrodynamic functioning. Mainly governed by wind and semidiurnal M2 tides, currents are generally strong in intensity (mainly > 0.5 m.s-1 ) outside the bay. Inside the bay, their intensity are less than 0.3 m.s-1 and generally oriented to the south of the bay due to the influence of the trade winds (NE). Due sometimes to the influence of W and/or SW winds, the coastal circulation of the bay is oriented from the south to the north, impacting its northern part.

Download Full-text

The stratigraphy of the Neogene-Quaternary succession in the southwest Netherlands from the Schelphoek borehole (42G4-11/42G0022) – a sequence-stratigraphic approach

Netherlands Journal of Geosciences – Geologie en Mijnbouw ◽

10.1017/s0016774600023556 ◽

2007 ◽

Vol 86 (4) ◽

pp. 317-332 ◽

Cited By ~ 9

Author(s):

A.A. Slupik ◽

F.P. Wesselingh ◽

A.C. Janse ◽

J.W.F. Reumer

Keyword(s):

The Netherlands ◽

Coastal Area ◽

Late Quaternary ◽

Tidal Channel ◽

The South ◽

Glacial Cycles ◽

Sequence Stratigraphic ◽

The North ◽

Mammal Fauna

AbstractWe investigate the stratigraphy of Neogene and Quaternary intervals of the Schelphoek borehole (Schouwen, Zeeland, the Netherlands). The Breda Formation (Miocene-Zanclean) contains three sequences separated by hiatuses. The Oosterhout Formation (Zanclean-Piacenzian) contains at least two sequences. This formation is overlain by seven sequences of the Gelasian Maassluis Formation that almost certainly represent glacial cycles. The three lowermost sequences are provisionally assigned to the Praetiglian (MIS 96, MIS 98 and MIS 100). A large hiatus exists between the top of the Maassluis Formation and the base of the late Middle to Late Quaternary succession. Due to extensivein situreworking of older strata (including fossils) at the base of several of the formations, their exact boundaries are difficult to establish. The Neogene succession in the Schelphoek borehole is compared to the stratigraphic successions in the Antwerp area to the south and the Dutch coastal area and continental platform to the north. Finally, the stratigraphic context of the Gelasian (‘Tiglian’) mammal fauna dredged from the bottom of a major tidal channel in the adjacent Oosterschelde is assessed by comparison with the Schelphoek borehole.

Download Full-text

Morphological and molecular characterization of a new species of Atlantic stalked barnacle (Scalpelliformes: Pollicipedidae) from the Cape Verde Islands

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315411000166 ◽

2011 ◽

Vol 91 (7) ◽

pp. 1537-1545 ◽

Cited By ~ 3

Author(s):

Javier Quinteiro ◽

Jorge Rodríguez-Castro ◽

Pedro López ◽

Luis F. López-Jurado ◽

Nieves González-Henríquez ◽

...

Keyword(s):

New Species ◽

Charles Darwin ◽

Taxonomic Status ◽

Molecular Data ◽

Cape Verde ◽

Eastern Pacific ◽

Cape Verde Islands ◽

The North ◽

North Eastern ◽

Central Eastern

The taxonomy of pedunculate cirripedes belonging to the genus Pollicipes has essentially remained unchanged since Charles Darwin described them in his exhaustive work on the Cirripedia. This genus includes three species of stalked barnacles: Pollicipes pollicipes in the north-eastern Atlantic, P. polymerus in the north-eastern Pacific and P. elegans in the central-eastern Pacific. However, a population genetics analysis of P. pollicipes suggested the presence of a putative cryptic species collected from the Cape Verde Islands in the central-eastern Atlantic. This study examines the morphology of these genetically divergent specimens and compares them with that of representative Atlantic samples of the biogeographically closely related P. pollicipes and with the poorly described P. elegans. Molecular data, including mitochondrial COX1 and nuclear ribosomal interspaces sequences, were obtained for all species of the genus Pollicipes. Morphological distinctiveness, diagnostic characters, congruent divergence level and monophyletic clustering, at both nuclear and mitochondrial loci support the taxonomic status of this new species, Pollicipes darwini.

Download Full-text

Finding Alcatrazes and early Luso-African settlement on Santiago Island, Cape Verde

Antiquity ◽

10.15184/aqy.2017.104 ◽

2017 ◽

Vol 91 (358) ◽

Cited By ~ 4

Author(s):

Christopher Evans ◽

Marie Louise Stig Sørensen ◽

Michael J. Allen ◽

Jo Appleby ◽

Tania Manuel Casimiro ◽

...

Keyword(s):

Cape Verde ◽

The South ◽

Cape Verde Islands ◽

Main Island ◽

South West ◽

Santiago Island

After the Portuguese discovered the Cape Verde Islands in AD 1456 they divided its main island, Santiago, into two governing captaincies. The founding settlement in the south-west, Cidade Velha, soon became the Islands’ capital and a thriving trade centre; in contrast, that in the east, Alcatrazes, only lasted as an official seat from 1484–1516 and is held to have ‘failed’ (see Richter 2015).

Download Full-text

OFFSHORE ARTIFICIAL STRUCTURES AND THEIR INFLUENCE ON THE ISRAEL AND SINAI MEDITERRANEAN BEACHES

Coastal Engineering Proceedings ◽

10.9753/icce.v18.110 ◽

1982 ◽

Vol 1 (18) ◽

pp. 110

Author(s):

Vaacov Nir

Keyword(s):

Sandy Beaches ◽

The South ◽

The North ◽

Northerly Direction ◽

Levantine Basin ◽

Beach Sediments ◽

Port Said ◽

North Beach ◽

North Sinai ◽

Quartz Grains

The Israel Mediterranean shore forms a gentle curve from an almost easterly direction in north Sinai to an almost northerly direction in Israel. This shore forms the southeastern corner of the Levantine Basin which itself forms the extreme eastern part of the Mediterranean Sea. The length of the Israel shoreline from Rosh Haniqra near the Lebanese border to northern Sinai in the south is about 230 km, while the Sinai coast from Rafah to Port Said (Fig.1), is almost 200 km long. The coastline region consists largely of Quaternary carbonate cemented quartz sandstone, known by local name "kurkar". Recent faulting is responsible for the shape and, to a certain extent, for the morphology of large parts of the central coastline, which is characterized by kurkar cliffs (Neev et. al_. , 1973 it 1978).Wide sandy beaches are found in the southern parts, while an abraded rocky platforms occur mainly in the central and northern parts, where the beaches are narrow having kurkar cliffs at their backshor.e side. Four different morphological sections can be found in the Israel Mediterranean shore, (Nir, 1982). These differ in their beach and inland morphology on one hand, and in their sedimentological properties on the other. The four different sections from north to south are: 1) Rosh Haniqra to Akko. A sedimentological1y isolated region, bounded on both the south and north. Beach sediments are mostly of local calcareous material of marine origin. Akko promontory is the most northern limit of Nile derived sands and plays as the recent edge of the Nile sedimentary cell (Nir, 1980). 2) Haifa Bay. Wide sandy beaches, bounded on the north by the Akko promontory, and by the Carmel "nose" on the south. 3) Mount Carmel coastal plain, is sedimentologically somewhat isolated region with relatively narrow beaches and small kurkar cliffs. Sediments consist of both local and imported components. 4) The kurkar cliffs and sandy beaches from Caesarea to Rafah. Beaches of differing width having quite uniform petrographic components, mostly quartz grains originating from the Nile river and transported along the Sinai beaches to the Israeli beaches. Some of the present beach components are derivated from the abraded kurkar cliff.

Download Full-text

Ventilation time scales of the North Atlantic subtropical cell revealed by coral radiocarbon from the Cape Verde Islands

Paleoceanography ◽

10.1002/2015pa002790 ◽

2015 ◽

Vol 30 (7) ◽

pp. 938-948 ◽

Cited By ~ 3

Author(s):

Alvaro Fernandez ◽

Thomas J. Lapen ◽

Rasmus Andreasen ◽

Peter K. Swart ◽

Christopher D. White ◽

...

Keyword(s):

Time Scales ◽

North Atlantic ◽

Cape Verde ◽

Cape Verde Islands ◽

Ventilation Time ◽

The North ◽

The North Atlantic ◽

Subtropical Cell

Download Full-text

Climatic factors influencing fluxes of dissolved organic carbon from the forest floor in a continuous-permafrost Siberian watershed

Canadian Journal of Forest Research ◽

10.1139/x05-150 ◽

2005 ◽

Vol 35 (9) ◽

pp. 2130-2140 ◽

Cited By ~ 32

Author(s):

A S Prokushkin ◽

T Kajimoto ◽

S G Prokushkin ◽

W H McDowell ◽

A P Abaimov ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Forest Floor ◽

Climatic Factors ◽

Soil Layer ◽

The South ◽

The North ◽

Doc Production ◽

Doc Flux ◽

Forest Floor Leachates

Fluxes of dissolved organic carbon (DOC) in forested watersheds underlain by permafrost are likely to vary with changes in climatic regime that increase soil moisture and temperature. We examined the effects of temporal and spatial variations in soil temperature and moisture on DOC fluxes from the forest floor of contrasting north- and south-facing slopes in central Siberia. DOC fluxes increased throughout the growing season (JuneSeptember) on both slopes in 2002 and 2003. The most favorable combination of moisture content and temperature (deepest active soil layer) occurred in September, and we believe this was the primary driver of increased DOC concentrations and flux in autumn. Total DOC flux for JuneSeptember was 12.617.6 g C·m2 on the south-facing slope and 4.68.9 g C·m2 on the north-facing slope. DOC concentrations in forest floor leachates increased with increasing temperature on the north-facing slope, but were almost unaffected by temperature on the south-facing slope. Our results suggest that water input in midseason from melting of ice or precipitation events is the primary factor limiting DOC production. Significant positive correlations between amounts of precipitation and DOC flux were found on both slopes. Dilution of DOC concentrations by high precipitation volumes was observed only for the forest floor leachates collected from the north-facing slope. Our results suggest that global warming will result in increased DOC production in forest floors of permafrost regions, and that precipitation patterns will play an important role in determining the magnitude of these changes in DOC flux as well as its interannual variability. However, the longer-term response of soils and DOC flux to a warming climate will be driven by changes in vegetation and microbial communities as well as by the direct results of temperature and moisture conditions.

Download Full-text

The Increasing Trend of Black Carbon and Organic Carbon in Jordan During the Period of 2007 to 2018

Nature Environment and Pollution Technology ◽

10.46488/nept.2021.v20i03.004 ◽

2021 ◽

Vol 20 (3) ◽

Author(s):

K. M. Hamasha

Keyword(s):

Organic Carbon ◽

Black Carbon ◽

Mass Concentration ◽

Mass Density ◽

Carbonaceous Aerosol ◽

The South ◽

Surface Mass ◽

The North ◽

Scattering Measurements ◽

Increasing Trend

During the last decades, carbonaceous aerosol extinctions such as black carbon and organic carbon extinctions exhibit an increasing trend across the globe. Measurements of carbonaceous aerosol in Jordan were done using satellite data during the period 2007 to 2018. These measurements were done in four locations of Jordan - Irbid in the north, Amman and Az-Zarqa in the middle, and Ma’an in the south. Black carbon extinction in Jordan increased slightly (slope = 0.0001) during this period, while organic carbon extinction increased slightly (slope = (0.7 – 10) x10-5) in three locations and decreased slightly in one location (Irbid location (slope = -2x10-5)). Organic carbon extinction measurements were greater than black carbon extinction measurements in all locations with varying ratios depending on the location of the measurements. Black carbon and organic carbon scattering measurements have the same behavior as extinction, with larger values in the north and smaller values in the south. Scattering values of organic carbon are larger than black carbon scattering values. Scattering values of organic carbon increased slightly in all locations (slope = 0.0001) while scattering values of black carbon decreased in three locations (Irbid, Amman, and Ma’an) and increased in one location (Az-Zarqa). Column mass density and surface mass concentration measurements show that organic carbon had larger values than black carbon in all locations besides that both organic carbon and black carbon had values decreasing when we go from north to south.

Download Full-text